3000, last I heard. But that was one or two years ago. I think it was raised to 3500 recently. May be wrong.
3999 right now I believe.
With regards to nymphs/marks, what I'd really like to see is some options under "account settings" or something like that
which all default to off such as "Allow selling rares?", "Allow selling non-rare upgraded cards?", "Allow selling nymphs?" etc.
Defaulting to off means new players won't accidentally sell anything, but people who voluntarily
want to sell off a pile of stuff can just go in, allow selling upgraded cards, and then sell off a pile of stuff without having to see the message every few clicks.
Seems like the only drawback here would be the (relatively small) bit of coding time required, but otherwise it'd address all the issues.